Arwi (لسان الأروي lisān-ul-arwī or lisān al-arwi; lit. "the Arwi tongue"; அரபு-தமிழ் arabu-tamil) is a written register of the Tamil language that uses an Arabic alphabet. It typically has extensive lexical influences from the Arabic language. Arwi was used extensively by the Muslim minority of Tamil Nadu state of India and Sri Lanka.^[when?] A few Islamic schools still teach the basics of Arwi as part of their curricula.

Arwi was an outcome of the cultural synthesis between seafaring Arabs and Tamil-speaking Muslims of Tamil Nadu. It had a rich body of work in jurisprudence, sufism, law, medicine, and sexology, of which little has been preserved. It was used as a bridge language for Tamil Muslims to learn Arabic. Many hadith manuscripts have been found. Most of the fiqh books, particularly those of Imaam Shaafi and Imaam Abu Hanifa, have been found in Arwi. There was also a translation of the Bible into Arwi in 1926. Arwi contributed immensely^{[citation needed]} to the education and progression of Muslim women in South India and Sri Lanka. Arwi-educated women were active participants in the social fabric of society playing vital roles in education, medicine and even politics.